Brake



P J. R. HEIDLOFF" 2,092,251

BRAKE Filed March 13 1935 g Sheets-Sheet -1 22 INVENTOR.

JOSEPH 4? H2704 arr ATTORNEY 35 my invention;

Patented Sept. "7, 1937 PATENT OFFICE mums Joseph B. Heidlofl, South Bend, Ind assignor to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application March 1a, 1933, sci-In No. 861,612

3 Claims. (01. (so-54.0)

This application relates to brakes for automotivevehicles and most particularly to brake systems employing hydraulic actuating means.

One of the objects of the invention disclosed herein is to insure the adequate'sunply of liquid to the system at all times and to eliminate air and other gases from the operating parts. A further object of the invention is to provide simple and eiflcient means for fllling the system 10 with liquid and for eliminating air therefrom when the system is first placed in operation.

A further object is to provides simple system in which the liquid is normally under super- -'atmospheric pressure whereby the tendency of air to leak in is minimized.

,A feature of the invention is the specific arrangement of an auxiliary chamber within the master cylinder connected with the reservoir and having two ports leading to the master cylinder,

one of which is controlled by a check valve.

A further feature of the invention is the combination of a check valve interposed between the master cylinder and the conduits leading to the wheel cylinders and a screw designed normally 25 to make the valve inoperative.

'A further feature is the specific spring pressed plunger which maintains the liquid in the reservolrunder pressure at all times.

. Further features and objects of the invention 30 will be apparent after a reading of the subjoined specification and claims and after consideration of the accompanying drawings,.in which:

Figure 1 is a view showing in section a master cylinder and a reservoir constructed according to Figure 2 is a sectional view showing an alterate form of master cylinder; and

Figure 3 is a sectional view showing a' third form' oi master cylinder.

Refe'rring particularly to Figure 1 of the drawings I have shown a mastercylinder Ill and a reservoir ii. The master cylinder is formed with a pressure chamber i4 and with an outlet I! through which liquid is adapted to flow out to 45 the brake operating-motor or'motors; Adapted 1 to be reciprocated in the pressure chamber i4 is v a'piston i6 having associated therewith a rubber packing cup l8. The packing cup is secured to.

the piston by a metallic button I8 molded in the 50 rubber and having a flange fltting in an eccen- 55 rocated through a piston rod 28 secured for substantially universal movement to the rear end thereof. The piston rod maybe operated by any suitable means, as for instance by -a foot pedal. The rear end 01' the cylinder i is provided with a so washer 22 held in place by a spring ring :4 and serving to limit the rearward movement oi the piston ll. There is also provided for the rear end of the piston a flexible boot 28 which serves to keep out dust. etc.

The master cylinder is provided with an inclined projection 28 which is formed with 'a threaded recess 38. There are also formed in the projection 28 'a pair of bores or inlet ports 82 and 34. cylinder and terminates at its lower end in a very small opening 88 leading to the pressure chamber ll just in advance oi the normal position of the cup l8. The latter is inclined substantially concentric with the projection 28 and leads to the front of the pressure chamber I l. Screwed into the recesss 88 is a threaded plug 38 which is formed with an annular groove 48, a-central passageway 42 and a concentric tapered recess 44. 1

The annular groove 48 is designed to register with the port 32 and is connected by radial ports such as 48 with the passageway 42. Positioned in the recess 44 is a check valve formed by a tapered rubber disk packing ll normally seated on the tapered shoulder of the recess 44 and urged toward its seat by a spring 48. The valve has molded into it when formed a guide plug 48 which extends into the smaller portion'oi the passageway. The spring 88 bears at its opposite end on a guide disk 50 held in place in plug 88 by spring clip Bi. V

The outer end of plug 88 is formed with a threaded portion 52 on which is secured a coupling it by which the plug is secured to a .conduit 56 leading to the reservoir ii.

The reservoir I2 is designed to keep a reserve supply of liquid. It is formed by a light cylinder 88 provided with upper and lower end caps 62 and 84 respectively. The lower cap 64 is formed with an annular flange 88 into which is screwed the bored plug 88. The upper end of the conduit The former extends radially of the Within the reservoir i2 is a piston 12 rained by metallic guides I4 and 18 positioned oneach side of rubber cup 18 and clamped, to each other by the bolt 88. The guide It is formed with apertures 15 and the guide "is formed with apertures II. Theguide I6 alsoserves to limit the downward movement of the piston. The bolt 88 is provided with a ring 82 to which is secured the lower end of a chain 84. The upper endof the chain 84 is secured to theupper cap 82 which is in turn secured to a pullring 88. By means of the ring 86 the piston I! may be raised to the top of the reservoir. A spring 88 bears at its lower end on piston 12 and at its upper end on a locking ring 88.

The master cylinder ill shown in Figure 2* may be used withior without a spring pressed piston in the reservoir similar to it. It is provided with a check valve H90 positioned in the front end thereof. The valve is formed by an annular perforated metallic guide 192, an annular rubber cup 894 and an annular metallic washer N6, the latter having a diameter smaller than the internal diameter of the cylinder and smaller. than the diameter of the rubber cup i194 serves as a guide for a spring i9? bearing at its forward end on the valve ltd and at its rear end on a metal cup its which is associated with the rear end of the tube.- The cylinder H0 is formed with an extension iii into which the guide tube 698 is adapted to extend when the piston 'i it is pushedforward;

The master cylinder shown in Figure 3 also may be used with or without the spring pressed piston in the reservoir. The cylinder did is formed with a partition tit. The partition is formed with non-alignedbores 265 and 2!? each extending longitudinally of the cylinder andonly partially through the partition. Extending through the partition and'through the sides oi.

the cylinder are aligned radial bores 2E8, 225

' and 223, the first having the smallest diameter ton through the ports 35 and the last having the largest. A threaded plug 225 having a recess 22? closes the bore223 and a screw 229 formed with an extension Edi extends through the bore me. A valve member 233 rests on a, valve seat 235 formed at the lower side or the bore Hi and is urged toward closed posi-. tion in contact with sad seat by a spring ml. The spring has its outer end positioned in re-- cess 2271'.

The operation of the devices disclosedis as iollows: Assume that the braking system is empty. The ring- 88 together with the cover $2 is titted from the reservoir 82 and brake fluid is poured in substantially to the top of the reservoir. The cover 62 together with the ring 56 is raised further thus acting through the chain at to raise the piston 12. Fluid is by-passed below the pisand W- and past the cup 38.

When piston 72 has been raised to the top of the reservoir i2, the ring 85 is released which causes the piston to exert pressure on the liquid in the reservoir and force the liquid through the conduit 55 to the master cylinder id passing through ports dB; and 32 and possibly forcing valve Ill from its 'seat. If the system is not completely filled the process may be repeated. The process may be expedited by 1 operating master piston it, thus pumping liquid past valve 41. When the system has been filled with liquid the brakes are operated by operating master piston iii in the usual way. I master piston should return more rapidly than fluid from the wheel cylinder, a surplus of fluid is admitted into the master cylinder. Should the amount or liquid .in the master cylinder be too large, the excess flows back to the reservoir by. way of ports 32 and 45. .In filling the system shown in Figure 2, operation of the piston tit pumps liquid from the reservoir through the valve M1 and past the valve i913. This is efiective even if the piston H6 is not allowed to return to uncover the port 236. The piston M6 on its rearward stroke draws liquid into the pressure chamber past the check valve Eel. On the forward stroke the 1 A hollow tube 893- is adapted to slide through the guide cup and washer and- Ii, however, the r check valve it? closes and the liquid is forced past the cup I98 which-serves as a second valve. Thus the cylinder acts just as a pump, being provided with the two valves Hi and itii between which the piston i it is adapted to reciprocate. During normal operation excess liquid ahead of the valve is!) may escape (when the piston is at its rearward position) through the tube Q98. .The'meta'l cup I99 normally seats upon the rubber cup its, being held there by the spring iti. However, whenever the pressure in the system ahead of the cup let exceeds that rearward of the valve 998 plus the pressure of the-spring iQ'l,

' this pressure (being present also in the cup Hot by reason or the connection through the tube are) is adapted to raise the cup its from its seat and to allow the escape of liquid back into the pressure chamber. Thus liquid is allowed to return upon the release of the brakes- If the parts are in their normal released position, the liquid then escapes through the port 235 back to the reservoir. The valve formed by the cup 889 thus serves as a check valve when operating the brakes as well as when priming the system.

Similarly, operation of the piston 29$ pumps liquid through the valve 247 and past the valve 233. After the system is filled with liquid, the

the system.

It is to be understood that the above described embodiments of my invention are for the purpose of illustration only and various changes maybe i made therein without departing from the spirit Y and scope of the invention. J

I claim: -f

i. In hydraulic brake apparatus, a cylinder having an outlet leading to the brakes, a piston in said cylinder, a valve associatedwith said outlet, and a screw normally bearing on saidvalve to maintain the outlet open, said cylinder having a radial bore and a recessed plug screwed into said bore, and said valve having a spring seated within said recess for urging it to closed position except when pressure is applied thereto from within said master cylinder or when said valve is held open by said screw.

2. In hydraulic brake apparatus, a master cyirecess formed on one of the outer'iaces thereof,

and with a pair of inlet ports leading from said recess to said chamber, and having an outlet leading to the brakes; a piston in said pressure chamber; a valve associated with said outlet; a spring for urging said valve toward closed position; a screw normally bearing on said valve to maintain the outlet open; and a valve for controlling one oi said inlet ports. said last named valve comprising a plug secured in said recess and formed with a passageway having a tapered shoulder, aguide plug extending within the smaller portion of saidpassageway. a rubber tapered disk adapted to-bear on said shoulder and molded around said guide plug: bearing on said disk.

. JOSEPH R. HEIDI-OFF.

and a spring 

